A lot of confusion swirls around the names of two common exhaust mods. The "Gundo Hack" and "Fister mod" are two completely different mods which result in different exhaust notes.

The Gundo PSE style mod

Gundo PSE style mod

This is a Porsche Sport Exhaust (PSE) style exhaust without the inline solenoid switch enabling it to be opened or closed. With a Gundo you're open all the time - perfect! This mod is a partial muffler bypass. All gases pass through at least a portion of the muffler. Some of the exhaust takes a shorter trip and only flows through the first resonant chamber of the muffler then goes straight to the output pipe. To do this mod you open up the capped exhaust port in the muffler and connect it to the output pipe of the muffler with a stainless tube. The larger diameter the tube, the deeper and richer the exhaust note. My 2004 cabriolet has the Gundo hack with a 2" pipe. Because all exhaust passes through at least a portion of the muffler the sharper bark of the Fister mod isn't present. Glorious sound, no drone and amazing under full throttle.

Second, the Fister mod

Fister mod

Whereas the Gundo runs all exhaust through at least a portion of the muffler, the Fister mod is a true muffler bypass for a portion of the exhaust The input and outflow pipes are joined with a tube directly. Results are a bit louder, raspier and there is a bit more of a sharp bark to the exhaust note without being too loud. The larger the diameter of the pipe used, the deeper and throatier the exhaust note. This is the mod that will find a home on my C4S in the near future and is likely the perfect option for a coupe. The Fister mod is done professionally by Darren Fister and you can see his work at fdmotorsports.net. While many people do their own hack for a Fister mod, FD offers a guaranteed job with a great selection of finishes.

To sum up, these are two excellent exhaust modifications. While they don't offer real horsepower gains, they will definitely sound at least 50 hp faster. As a warning, your fuel economy will suffer because you won't be able to stop yourself from putting your right foot down a lot more aggressively. Enjoy!

I will admit it looks like a lot but installed all you see is the stock exhaust tip. All you hear is a raspy slightly tinny bad to the bone exhaust tone. I've watched many youtube 996 rally car vids and it sounds pretty much like those except I'm never on a narrow dirt road. I'll work on getting a vid attached but I'll say right now just putting a picture up was a stretch of my skills for me.